Proto / Loader

src/io/proto/loader.ts loads the Apollo HD-map proto schema using protobufjs. All .proto files are bundled with Vite's ?raw glob, so runtime is fully offline and Vitest reuses the same mechanism on Node.

Exported symbols

import * as protobuf from 'protobufjs';

export function loadApolloProtoRoot(): Promise<protobuf.Root>;
export function getMapType(): Promise<protobuf.Type>;

Source: src/io/proto/loader.ts:1-58.

`loadApolloProtoRoot()`

Returns the cached protobuf.Root once load('map_msgs/map.proto') has completed. The first call pays the parse cost (~5–15 ms); subsequent calls return the cached promise.

Implementation notes:

Glob injection — import.meta.glob('/src/proto/**/*.proto', { query: '?raw', eager: true }) embeds every proto file into the bundle. Works in Vite and Vitest.
resolvePath override — Apollo proto imports look like map_msgs/map_lane.proto, root-relative under src/proto/. The default protobufjs resolver would join with the importing file's directory and yield map_msgs/map_msgs/…. We override to (_, target) => target.
Deferred fetch callback — done(...) runs inside Promise.resolve().then(...) so protobufjs' internal queued counter never dips to 0 mid-traversal. A synchronous callback triggers a premature resolveAll() and surfaces as "no such Type" errors.

const root = await loadApolloProtoRoot();
const Map = root.lookupType('apollo.hdmap.Map');

`getMapType()`

Convenience: (await loadApolloProtoRoot()).lookupType('apollo.hdmap.Map'). Used by binCodec, textCodec, and adapter.

const Map = await getMapType();
const obj = Map.toObject(Map.decode(bytes));

Why `?raw` instead of pbjs codegen

No extra build step. Editing a proto only requires vite, no pbjs invocation.
Reflection at runtime. Map.fields, field.resolvedType remain available, which is what apolloMapToLonLat needs to walk every PointENU recursively.
Bundle size. ?raw strings plus a single protobuf.Root is ~150 KB gzipped; pre-generated JSON is no smaller and loses reflection.

Flow

Errors

Cause	Surface
Missing file in `PROTO_SOURCES`	`Error: Proto file not found in bundle: <name>`
Synchronous fetch callback (regression)	`Error: no such Type ...` from `protobufjs.resolveAll()`
Invalid PROJ string upstream	Surfaced in `adapter.ts`, not here

Tests

src/io/proto/__tests__/loader.test.ts covers cold load and cache reuse, plus a regression test for the deferred fetch callback.

Contributors

kent

Changelog

Last edited 4 minutes ago

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Proto / Loader ​

Exported symbols ​

loadApolloProtoRoot() ​

getMapType() ​

Why ?raw instead of pbjs codegen ​

Flow ​

Errors ​

Tests ​

See also ​